My occasional search for specific CPU model strings finally revealed what seems to be the first sign of a working AMD Kaveri ES in the wild. So this is categorized as CPU family 21 (15h - Bulldozer) model 48 (30h). The measured performance numbers (BOINC Whetstone/Dhrystone) are rather low, which indicates a low clock frequency during that measurement run, possibly caused by missing power management or other CPU drivers.

The ES code 2M186092H4467_23/18/12/05_1304 tells us even more. According to earlier observations (here and here), the four numbers in the middle part tell a bit about clock speeds. If the first one is not 00 (no turbo, see Kabini ES), it indicates a turbo clock of 2.3GHz. The "18" stands for 1.8GHz nominal frequency. I'm not so sure about the "12". It could stand for 1.2Ghz North Bridge clock. Finally the "05" indicates a 500MHz GPU clock. The right part "1304" is the GPU code, which - thanks to earlier revelations - can be identified as AMD1304.1 = "KV SPECTRE MOBILE 35W (1304)" (source).